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HIRUNDINiE. HIRUNBO. 
co3ca very small; cloaca oblong. Trachea with four pairs 
of inferior laryngeal muscles.- Nostrils small, linear- 
oblong. Eyes of moderate size. Aperture of ear rather 
large, elliptical. Feet extremely short, slender; tarsus 
bare or feathered, always with some scutella below ; toes 
small, three before, one behind, bare and scutellate, or 
feathered, with the usual numberof joints ; claws rather 
long, moderately arched, compressed and laterally grooved, 
tapering to a very acute point. Plumage soft, blended ; 
bristles about the mouth very small ; wings extremely 
long, pointed, the outer two quills longest, and slightly 
incurved toward the end ; tail of twelve feathers, even or 
forked. Trachea with four pairs of inferior muscles. 
The Hirundinse feed entirely on insects, which they 
capture on wing. They are therefore obliged to retire 
southward, in autumn, from the colder and temperate 
regions. Their flight is extremely rapid and buoyant ; 
their ordinary cry a chirp, or twitter ; but most of them 
have a modulated song. They nestle in holes, or against 
the face of rocks, buildings, or trees, forming their nest 
of mud, or of twigs held together by a glutinous substance, 
and laying four or five white eggs, which are either plain 
or spotted. 
GENUS XIX. HIRUNDO. SWALLOW. 
Bill very short, much depressed, of a triangular form ; 
upper mandible with the dorsal line convexo-declinate, the 
edges slightly inflected, with a distinct notch, the tip slen- 
der, but blunt ; lower mandible with the angle very large 
and wide. The characters of the digestive apparatus, organs 
of sense, and limbs, as above. Plumage soft, glossy on the 
upper parts ; the feathers oblong ; bristle-feathers at the 
base of the upper mandible scarcely apparent ; wings ex- 
tremely long, pointed, with the outer two quills longest ; 
tail emarginate or forked. 
As in the genus Buteo, one species has the tarsi bare, 
while they are feathered in another ; so may it be with 
